U0040 Lincoln Zephyr Diagnostic Trouble Code

U0040 Lincoln Zephyr code definition:
U0040 is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code for Lincoln Zephyr.

U0040 Lincoln Zephyr is defined as Ignition Coil B Primary/Secondary Circuit Malfunction.This code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II tool, or vehicles made since 1996 up to present. The spark should have a light tan color. If the sensor probe comes with white and chalky parts, this means it has been lagging between switching phases, and should be replaced.

Symptoms

Symptoms of a U0040 Lincoln Zephyr diagnostic trouble code may include:
  • The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
  • Faulty PCM
  • If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected
  • Diminished fuel efficiency
Place of U0040 in engine

Possible Causes :

  • An air leak forward of the DPF will change the sensor readings resulting in the code
  • Rusty exhaust systems, cracked exhaust manifolds or damaged or missing gaskets or donuts will cause air leaks.
  • Fuel with a large percentage of sulfur will clog the DPF quickly

Common Misdiagnoses

  1. Exhaust Gas Recirculation System Valve 1 Problem
  2. BBV Sensor Circuit Low Voltage Problem
  3. Transmission Engaged At High Throttle Angle Problem
  4. Cruise Inhibit Control Circuit Problem
  5. TFP Valve Position Switch-Drive Without Drive Ratio Problem

Repair Processes :

You might continue by connecting the scanner to the vehicle diagnostic connector and retrieving all stored codes and freeze frame data. With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power wire and the black voltmeter lead connected to ground. If the engine displays a miss and there wasn't a code, determine which cylinder is misfiring. If the exhaust manifold is visible, spay or pour a small amount of water on each cylinder exhaust port. Water will evaporate immediately on good cylinders and slowly on the missing cylinder. If this can't be accomplished pull the plugs and check the condition.

Process Tips

Diagnostic trouble code U0040 Lincoln Zephyr is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.

Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before U0040 Lincoln Zephyr.

Fortunately, U0040 Lincoln Zephyr is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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